JP2001319337A - Optical information recording and reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately control the laser power of a semiconductor laser beam source even when a sampling signal of the sample holding is not outputted longer than the specified period. SOLUTION: The laser power of a bias level is detected at the time of recording operation, and the laser power is controlled on the basis of this detection, and also when the sampling signal to be outputted in accordance with the data length of the information recording on the optical disk for detecting the laser power of the bias level is outputted at intervals within the specified period, the control is changed over to the APC control for controlling the laser driving current value of an LD 2 so that the emitting power of the laser beam becomes constant in accordance with the level change of a power monitor current signal 109 corresponding to the level of the laser power, and when the sampling signal is not outputted longer than the specified period, the control is changed over to the ACC control for controlling the laser driving current value of the LD 2 with the control value independently of the level of the laser power.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical information recording / reproducing apparatus such as an optical disk drive for recording and reproducing information by irradiating a recording medium such as an optical disk with a laser beam from a light source such as a semiconductor element.

[0002]

2. Description of the Related Art Recently, with the spread of multimedia, an optical disk (recording medium) which is a read-only medium such as a music CD, CD-ROM, and DVD-ROM, and information recorded on the optical disk are reproduced. An information reproducing device that is an optical disk drive has been put to practical use.

In addition to a write-once optical disk using a dye medium and a rewritable MO disk using a magneto-optical (MO) medium, an optical disk that is a phase-change type medium has also attracted attention. An information recording / reproducing apparatus, which is an optical disk drive for recording and reproducing information, has also been put to practical use.

[0004] In particular, rewritable DVD media have received much attention as next-generation multimedia recording media and large-capacity storage media. The phase change medium is a recording medium that records information by reversibly changing the phase of a recording material between a crystalline phase and an amorphous phase.

The above-mentioned phase change type media does not require an external magnetic field unlike MO media and the like, and can record and reproduce information only by laser light from a light source composed of a semiconductor element such as a laser diode (LD). In addition, overwrite recording in which recording and erasing of information are performed at once by a laser beam is possible.

As a general recording waveform for recording information on the phase change type medium, there is a single-pulse semiconductor laser emission waveform generated based on, for example, an 8-16 modulation code. In single pulse recording, the recording mark may be distorted in tears due to animal heat,
There is a problem that the cooling rate is insufficient, the formation of the amorphous phase is insufficient, and a recording mark having low reflection with respect to the laser beam cannot be obtained.

Therefore, as a recording method for recording information on a DVD-based phase-change medium, as shown in FIG. 9, a mark is formed on the phase-change medium by a multi-pulse waveform laser beam using multiple stages of recording power. By doing
The problem described above is prevented.

As shown in FIG. 9 (c), the mark portion of the multi-pulse waveform has a leading heating pulse A for preheating the recording film of the phase change type medium sufficiently above its melting point.
, And a plurality of subsequent continuous heating pulses B and a continuous cooling pulse C therebetween. The light emission power (peak power) of the first heating pulse A and the heating pulse B is P
w, the emission power (bias power) of the cooling pulse C is P
b, assuming that the read power is Pr, the respective light emission powers are set so as to satisfy the relationship of the following Expression 1.

[0009]

## EQU1 ## Pw> Pb ≒ Pr (1)

[0010] The space portion of the multi-pulse waveform is
It is composed of an erase pulse D, and its emission power (erase power) Pe is set so as to satisfy the following equation (2).

[0011]

## EQU2 ## Pw> Pe> Pb (2)

By making the recording waveform a multi-pulse emission waveform in this way, an amorphous phase is formed in the mark portion of the phase change type medium by the rapid cooling condition of heating → cooling by the heating pulses A and B and the cooling pulse C. Since a crystal phase is formed in the space portion under the slow cooling condition of heating only by the erase pulse D, a sufficient reflectance difference can be obtained between the amorphous phase and the crystal phase.

Also, when information is recorded on a DVD-based dye medium, the recording mark cannot be accurately formed by single-pulse recording due to heat buildup, so that a laser beam having a multi-pulse waveform as shown in FIG. There has been proposed a recording method of forming a mark by using the above method.

As shown in FIG. 10C, the emission power (peak power) of the first heating pulse A and the heating pulse B is Pw, the emission power (bias power) of the cooling pulse C and the space D is Pb, and the read power is Pb. If the power is Pr,
Each light emission power is set so as to satisfy the following equation (3).

[0015]

Pw> PbＰPr (3)

When recording on the above-described phase change medium or dye medium, it is necessary to properly control the recording light emission power. Laser diode (L
As a control method of D), a method of driving a constant current to the LD irrespective of the fluctuation of the emission power is controlled by ACC control (AUTO).
MATIC CURRENT CONTROL).

However, since a drive current-light emission power characteristic of an LD easily fluctuates due to self-heating or the like, an APC is generally used as a means for stabilizing the light emission power.
Control (AUTOMATIC POWER CONTROL)
L).

In the APC control, a part of the light emitted from the LD is made incident on a photodetector (PD), and the LD drive current is controlled using a monitor current generated in proportion to the light emission power of the LD.

Here, when only information reproduction is considered,
Generally, a high frequency current is superimposed on an LD drive current for noise suppression, but since it is a DC constant current, APC control can be easily realized by forming a feedback loop of a relatively low band. be able to.

However, when APC is performed during recording,
Since the recording power changes at a high speed to form a mark and a space, some control is required. For example, CD
System or DVD system, DSV (DIGITA
If a low-bandwidth feedback loop is configured by utilizing the fact that L SUM VALUE becomes zero, the recording power can be controlled with a simple configuration as in the case of reproduction, but accurate power control is required. Can not.

In order to solve such a problem, conventionally, the level (bias level for the dye type medium, erase level for the phase change type medium) during the period in which the space data is output is relatively sampled and held. There has been an optical information recording / reproducing apparatus (for example, see Japanese Patent Application Laid-Open No. 8-96364) in which a bias level and an erase level during recording are accurately controlled by a low-band detection / control circuit.

In such an optical information recording / reproducing apparatus,
When recording is to be performed on a DVD-based phase change medium or a dye-based medium, multi-pulse light emission is performed when recording mark data. Therefore, when detecting recording power, long space data is output. If the sample-and-hold operation is performed during the operation, the detection / control circuit can be configured with a lower band.

For example, when recording is performed on a CD-R medium with a recording waveform as shown in FIG. 11, a SYNC frame is generated every SYNC frame (588 channel clock = 588T).
Since the data of the 11T space and the 11T mark are output as the C code, the sample and hold may be performed when the 11T space data is output.

[0024]

However, in the above-described conventional optical information recording / reproducing apparatus, when recording on a DVD-based medium, a SYNC frame (1488) is required.
The SYNC code output every T) is a 14T mark or 1 according to a predetermined rule in order to make DSV zero.
Since the 4T space is selected, the 14T space data is not always output periodically. Also, long space data other than the SYNC code is expected to occur stochastically within a certain period of time, but is not guaranteed as a modulation rule.

Therefore, when controlling the laser power in an analog manner based on the output value of the sample and hold circuit, if the sampling signal is not output for a predetermined period or more, the output decreases based on the droop characteristic of the sample and hold circuit, and abnormal light emission occurs. There was a problem of inviting.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to make it possible to accurately control the laser power of a semiconductor laser light source even when a sampling signal of a sample hold is not output for a predetermined period or more. Aim.

[0027]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention irradiates a semiconductor laser light source with a laser beam on a recording medium by causing a semiconductor laser light source to emit pulse light based on a predetermined light emission rule. Information comprising a pulse having a length of an integer multiple of one or more of a channel clock cycle based on a predetermined recording modulation method by using binary laser power of a bias level and a peak level, and recording the information recorded on the recording medium. In the optical information recording / reproducing apparatus for reproducing, a laser drive current value of the semiconductor laser light source is controlled so that the emission power of the laser light becomes constant according to a level change of a signal corresponding to the level of the laser power. (1) a laser power control means for controlling a laser drive current value of the semiconductor laser light source at a constant value irrespective of the laser power level; And Zapawa control means, said first
Switching means for switching between the laser power control means and the second laser power control means; detecting the laser power at the bias level during recording on the recording medium; and controlling the laser power based on the laser power at the bias level. In addition, when the sampling pulse output according to the data length of the information recorded on the recording medium for detecting the laser power of the bias level is output at intervals within a predetermined period, the switching unit performs 1
Switching to the laser power control means, controlling the laser drive current value by the control signal from the first laser power control means, and switching to the second laser power control means when the sampling pulse is not output for the predetermined period or more. Means for controlling a laser drive current value by a control signal from the second laser power control means.

Further, the semiconductor laser light source is caused to emit pulse light based on a predetermined light emission rule to irradiate the recording medium with laser light, and the recording medium is ternary laser light having a bias level, an erase level and a peak level. 1 of the channel clock cycle based on the predetermined recording modulation method depending on the power
Optical information recording / reproducing for recording information consisting of pulses having a length of an integral multiple of the above, erasing the information recorded on the recording medium, initializing the recording medium, and reproducing the information recorded on the recording medium In the apparatus, first laser power control means for controlling a laser drive current value of the semiconductor laser light source so that the emission power of the laser light is constant according to a level change of a signal according to the level of the laser power, A second controlling a laser drive current value of the semiconductor laser light source at a constant value irrespective of the laser power level;
Laser power control means, switching means for switching between the first laser power control means and the second laser power control means, detecting the erase level laser power during recording on the recording medium, and detecting the erase level laser power. In addition to controlling the laser power based on the power, sampling pulses output according to the data length of the information recorded on the recording medium for detecting the laser power at the erase level are output at intervals within a predetermined period. In this case, when the switching means switches to the first laser power control means, the laser drive current value is controlled by a control signal from the first laser power control means, and when the sampling pulse is not output for the predetermined period or more,
Switching to the second laser power control means,
It is preferable to provide a means for controlling a laser drive current value by a control signal from the laser power control means.

Further, in the above-mentioned optical information recording / reproducing apparatus, the first laser power control means may transmit the second information to the second laser power control means.
After switching to the laser power control means and outputting the sampling pulse, the switching means switches again to the first laser power control means to control the laser drive current value by the control signal from the first laser power control means. Means may be provided.

In the above-mentioned optical information recording / reproducing apparatus, the first laser power control means or the second laser power control means may be used.
A current for driving the semiconductor laser light source at the bias level is driven by a laser drive current control signal output from the laser power control means, and a current corresponding to the differential efficiency characteristic of the laser light emitted from the semiconductor laser light source It is preferable to provide a means for driving a current for causing the semiconductor laser light source to emit light at the erase level or the peak level by superimposing the laser light on the laser light.

Further, in the above optical information recording / reproducing apparatus, the sampling pulse is used as a trigger input,
A switching signal output unit for outputting a second laser power control switching signal for causing the switching unit to switch to the second laser power control unit after a predetermined period when the trigger input is received; If not, the second laser power control switching signal output from the switching signal output means to the switching means falls, and then the control means controls the second laser power control switching signal to rise when the sampling pulse is output. It is good to provide.

In the above-described optical information recording / reproducing apparatus, the apparatus operates based on a predetermined clock frequency, resets a count value by the sampling pulse, and switches to the switching means after a predetermined count after the count value is reset. A counting means for outputting a second laser power control switching signal for switching to the second laser power control means; and a second means for outputting from the counting means (counter) to the switching means when the sampling pulse is not output for a predetermined period or more. It is preferable to provide a means for resetting the counting means when the sampling pulse is output after the falling of the second laser power control switching signal and for controlling the second laser power control switching signal to rise.

Further, in the optical information recording / reproducing apparatus as described above, a differential signal between a control signal output from the first laser power control means and a control signal output from the second laser power control means is output. During the period in which the laser drive current value is controlled by the differential signal output means and the second laser power control means, the signal is output to the second laser power control means instead of a signal corresponding to the level of the laser power. By feeding back the output signal of the differential signal output means to the first laser power control means, a control signal output from the first laser power control means is changed to a control signal output from the second laser power control means. It is preferable to provide a means for maintaining the same level.

Further, in the optical information recording / reproducing apparatus as described above, a comparison signal obtained by comparing a control signal output from the first laser power control means with a control signal output from the second laser power control means. And a control signal output from the second laser power control means such that the control signals are periodically compared by the means so that the two control signals always have substantially the same level. Means for controlling the signal may be provided.

Further, in the optical information recording / reproducing apparatus as described above, there is provided means for setting the timing of outputting the sampling pulse when a period in which information to be recorded on the recording medium is "0" occurs for a predetermined period or more. Good.

The optical information recording / reproducing apparatus according to the first aspect of the present invention records and reproduces information by using binary laser power of a bias level and a peak level, and controls the laser power during recording by controlling the bias level. The laser power is detected, the laser power is controlled based on the detected laser power of the bias level, and a sampling pulse output according to the data length of the recording information for detecting the laser power of the bias level is determined. When the laser light is output at intervals within a period, the laser driving of the semiconductor laser light source is controlled by the first laser power control means so that the emission power of the laser light becomes constant according to the level change of the signal corresponding to the level of the laser power. Control the current value,
If the sampling pulse is not output for the predetermined period or more, the second laser power control means switches the laser drive current value of the semiconductor laser light source to a constant value regardless of the laser power level.

The optical information recording / reproducing apparatus according to the second aspect of the present invention records, erases, initializes, and reproduces information by using ternary laser power of a bias level, an erase level, and a peak level. As the laser power control, the erase level laser power is detected, the laser power is controlled based on the detected erase level laser power, and according to the data length of the recording information to detect the erase level laser power. When the sampling pulses output by the laser beam are output at intervals within a predetermined period, the first laser power control means makes the light emission power of the laser light constant according to a signal level change according to the laser power level. Control the laser drive current value of the semiconductor laser light source so that the sampling pulse If not force switches to control the laser driving current value of the semiconductor laser light source at a constant value regardless of the level of the laser power by the second laser power control means.

According to a third aspect of the present invention, in the optical information recording / reproducing apparatus, when a sampling pulse is output after switching from the first laser power control unit to the second laser power control unit, the first laser power control unit is again activated. To control the laser drive current value.

According to a fourth aspect of the present invention, an optical information recording / reproducing apparatus drives a current for emitting light at a bias level by a laser driving current output from the first laser power control means or the second laser power control means. By driving a current corresponding to the differential efficiency characteristic of the laser light on the laser light, the current for driving the laser emission at the erase level or the peak level is driven.

According to a fifth aspect of the present invention, in the optical information recording / reproducing apparatus, a sampling pulse is used as a trigger input, and after a predetermined period of the trigger input, the switching signal output means sends the switching means to the second laser power control means. A second laser power control switching signal to be switched is output, and when the sampling pulse is not output for a predetermined period or more, the second laser power control switching signal output from the switching signal output unit to the switching unit falls, and then the sampling pulse is output. When it is output, control is performed so that the second laser power control switching signal rises.

According to a sixth aspect of the present invention, in the optical information recording / reproducing apparatus, the counting means operates based on the predetermined clock frequency, resets the count value by the sampling pulse, and performs the predetermined counting after the resetting. Output the second laser power control switching signal, and if the sampling pulse is not output for a predetermined period or more, the second laser power control switching signal output from the counting means to the switching means falls, and then counts when the sampling pulse is output. The means is reset so that the second laser power control switching signal rises.

According to a seventh aspect of the present invention, in the optical information recording / reproducing apparatus, the differential signal output means outputs the control signal output from the first laser power control means and the control signal output from the second laser power control means. During the period when the differential signal is output and the laser power is controlled by the second laser power control means, the differential signal of the differential signal output means is replaced with the differential signal of the differential signal output means instead of the power monitor signal output to the first laser power control means. The control signal output from the first laser power control means is maintained at the same level as the control signal output from the second laser power control means by feeding back to the first laser power control means.

According to the optical information recording / reproducing apparatus of the present invention, the comparison signal output means compares the control signal output from the first laser power control means with the control signal output from the second laser power control means. By outputting a comparison signal as a result of the comparison and periodically comparing the control signal output from the first laser power control means and the control signal output from the second laser power control means, the two control signals are always substantially equal to each other. The control signal output from the second laser power control means is controlled so as to be at the level.

In the optical information recording / reproducing apparatus according to the ninth aspect of the present invention, the sampling pulse is output at a timing when a period in which the recording information is "0" occurs for a predetermined period or more.

[0045]

Embodiments of the present invention will be specifically described below with reference to the drawings. (First Embodiment) FIG. 1 is a block diagram showing a functional configuration of a main part of an optical information recording / reproducing apparatus according to one of the first to fifth and seventh to ninth embodiments of the present invention. FIG.
FIG. 2 is a block diagram showing an internal configuration of the bias level current driving device shown in FIG.

FIG. 3 is a timing chart of main signals output from the CPU shown in FIG. FIG.
FIG. 4 is a diagram showing a relationship between a driving current output from the bias level current driving device shown in FIG. FIG. 5 is a timing chart of various signals related to ACC control by the bias level current driving device shown in FIG.

The optical information recording / reproducing apparatus of the first embodiment shown in FIG. 1 employs an information recording method for recording (overwriting) DVD format code data on an optical disk which is a phase change medium (for example, a phase change disk). And
A mark edge (PWM: PULSE WIDTH MODU) using an 8-16 modulation code as a data modulation method
(LATION) recording, and using such an optical disk and recording data, a semiconductor laser beam is emitted in a multi-pulse manner and irradiated on a recording surface of a phase change medium to form a recording mark on the recording surface. Record information.

This optical information recording / reproducing apparatus performs
Peak power for forming a mark with multiple pulses:
Three types of recording power, Pw and bias power: Pb, and erase power for forming a space: Pe, are required.

First, a normal APC operation during recording in the optical information recording / reproducing apparatus will be described. The output currents of the erase level current driver 8 and the peak level current driver 9 are set by the erase level control signal 104 and the peak level control signal 105 output from the CPU 1, respectively.

The erase-level current driver 8 and the peak-level current driver 9 are specifically DACs,
The erase level superimposed current signal 106 and the peak level superimposed current signal 107 which are analog signals are output based on the LD drive current information digitally set from U1.

The bias level current driver 7 outputs a bias level drive current signal 108 by adopting the configuration shown in FIG. The LD drive device 4 calculates the respective drive current amounts of bias power: Pb, erase power: Pe, and peak power: Pw according to the bias level drive current signal 108, the erase level superimposed current signal 106, and the peak level superimposed current signal 107, respectively. decide.

Further, as shown in FIG. 3A, the CPU 1 stores information to be recorded on an optical disk (not shown) in an 8-bit format.
The signal is converted into a 16-modulation signal, and a multi-pulse waveform is generated as shown in FIG. 3D, and an erase power enable signal 101 and a peak power enable signal 102 are supplied to the LD driving device 4 according to the waveform. I do.

When the erase power enable signal 101 and the peak power enable signal 102 are at the high level "H", respectively, the LD drive device 4 outputs the erase level superimposed current signal 106 and the peak level superimposed current signal 1 of each level.
07 is appropriately superimposed on the bias level drive current signal 108 to supply a drive current to the laser diode (LD) 2.

More specifically, as shown in FIGS. 3B and 3C, when the semiconductor laser light is emitted at the erase level, the CPU 1 sets the erase power enable signal 101 to a high level "H", The LD drive device 4 superimposes the erase level superimposed current signal 106 on the bias level drive current signal 108 to make the drive current of the LD 2.

When the semiconductor laser light is emitted at the peak level, the peak power enable signal 102 is set to the high level “H”, and the LD driving device 4 applies the peak level superimposed current signal 107 to the bias level driving current signal 108.
Are superimposed to make the drive current of LD2.

When a driving current is supplied to the LD 2 by the LD driving device 4, the LD 2 emits a semiconductor laser beam, irradiates an optical disk (not shown), and records and reproduces information.

At that time, a part of the emitted light is changed to the monitor PD.
3, the monitor PD 3 outputs a power monitor current signal 109 proportional to the emission power to the I / V conversion circuit 5, and the I / V conversion circuit 5
The bias level current driver 7 performs APC control using the power monitor signal 110 by outputting the power monitor signal 110 obtained by current-voltage conversion.

In the bias level current driver 7, FIG.
As shown in the figure, the power monitor signal 110 output from the I / V conversion circuit 5 is branched into amplifiers 701 and 7 respectively.
03, and amplifies each of them and samples and holds them in sample and hold circuits 702 and 704.

The amplifier 703 and the sample hold circuit 704 are used for recording information on an optical disk of a phase change medium, and the amplifier 701 and the sample hold circuit 702 are used by an optical information recording / reproducing apparatus of a second embodiment described later. Used when recording information on an optical disk which is a dye medium.

The switch 709 outputs a media type selection signal 1
The output signals from the sample and hold circuits 702 and 704 are selected according to 16. FIG. 2 illustrates a case where the APC / ACC output comparison signal 114 is at a high level “H”.

In the optical information recording / reproducing apparatus of the first embodiment, when information is recorded on an optical disk of a phase change medium, the erase level is sampled and held. Since the bias level is sampled and held when recording information on the optical disk of the dye medium, the APC circuit 705 in the subsequent stage is used.
To make the output to be almost the same regardless of the media type,
The power monitor signal 110 is branched so that the gain of the amplifier 701 is set higher than the gain of the amplifier 703.

When long space data is output (for example, continuous space data of 10T or more), the sample hold circuit 704 performs power monitoring when the sampling signal 113 output from the CPU 1 changes from high level “H” to low level “L”. Sampling and holding signal 110, AP
Output to C circuit 705. At that point, switch 71
0, 711 and 712 select the high level “H”.

Target power value signal 1 output from CPU 1
12 is converted into an analog signal by the D / A converter 11 and then inverted by the inverting amplifier 708 based on the reference value voltage (VREF), added to the output signal from the sample hold circuit 704, and output to the inverting terminal of the APC circuit 705. Is done.

The APC circuit 705 is specifically an integration circuit, and forms an APC loop by outputting the output signal of the APC circuit 705 as the bias level drive current signal 108 through the switch 711 to the LD drive device 4.

The APC circuit 705 makes the sum signal of the output of the sample hold circuit 704 and the output of the inverting amplifier 708 equal to the reference voltage VREF, that is, the output of the sample hold circuit 704 and the target power value signal 11.
Control the output signal so that 2 is equal.

The bias level drive current signal 108 is digitized by the A / D converter 713 and output to the CPU 1 as a bias current drive current digital signal 115. Thus, the bias level drive current is controlled by sampling and holding the long space data.

Next, under the control of the CPU 1, the erase level superimposed current signal 106 and the peak level superimposed current signal 1
07 is superimposed with a constant current, but since the bias level is changed according to the change in the erase level,
The erase level is always power controlled analogly. The erase level superimposed current and the peak level superimposed current can be obtained based on the laser differential efficiency characteristics and the bias level drive current digital signal 115.

As shown in FIG. 4, the bias power: P
b, erase power: Pe, peak power: Pw, bias level drive current: Ib, erase level superimposed current:
In the case of ΔIe and the peak level superimposed current: ΔIw, the differential efficiency: η is obtained based on the following Expression 4. This differential efficiency: η is determined in advance.

[0069]

Η = (Pe−Pb) / ΔIe (4)

Based on the equation (4), the erase level superimposed current: ΔIe and the peak level superimposed current: ΔIw can be obtained by the following equations (5) and (6), respectively.

[0071]

ΔIe = (Pe−Pb) / η (5)

[0072]

ΔIw = (Pw−Pb) / η (6)

Next, an operation when the sampling signal 113 is not output for a predetermined period or more will be described. As described above, if the sampling signal 113 is not output for a long time, the output of the sample hold circuit 704 gradually decreases due to the droop characteristic, and the APC circuit 705 changes the output value according to the output of the sample hold circuit 704. The laser emission becomes abnormal.

If the sampling signal 113 is not output for a predetermined period, the control of the semiconductor laser light is temporarily controlled by ACC (AUTOMATIC CURRENT).
CONTROL).

That is, the digital signal output from the CPU 1 is converted into the ACC drive current signal 111 through the D / A converter 10 and is output as the bias level drive current signal 108 through the switch 711. The sampling signal 113 is output to the monostable multivibrator 714 as a trigger.

The monostable multivibrator 714 is triggered by the rising edge of the sampling signal 113, and always outputs a high level “H” while the trigger is output within a predetermined period (for example, 150 μs). The configuration is such that when a trigger is not output, it becomes low level “L”. Then, when the output of the monostable multivibrator 714 becomes L, the control is switched to the ACC control.

The monostable multivibrator 714 outputs an ACC control switching signal 750 to the switches 710, 711, and 712, respectively. FIG. 5 shows the timing of the operation. When the switch 711 becomes low level “L”, the ACC drive current signal 111 is output as the bias level drive current signal 108.

Then, when long space data of 10T or more is generated in this state and the sampling signal 113 is output, the output of the monostable multivibrator 714 becomes high level "H", so that the APC control is immediately returned to. .

When the switches 710 and 712 become low level “L”, the output of the APC circuit 705 and the ACC drive current signal 11 are output by the APC circuit output feedback circuit 706.
1 is fed back to the APC circuit 705,
The AP is set so that the output of the circuit output feedback circuit 706 is equal to the reference voltage: VREF, that is, the output of the APC circuit 705 is equal to the ACC drive current signal 111.
The C circuit 705 operates.

Thus, during the ACC control period, the AP
The output of the C circuit 705 can be prevented from being saturated, and the bias level drive current signal 108 can be settled promptly when returning to the APC control.

The comparator 707 includes an APC circuit 705
Is compared with the ACC drive current signal 111,
The C / ACC output comparison signal 114 is output to the CPU 1. The CPU 1 periodically refers to the APC / ACC output comparison signal 114, and
The output of the ACC drive current signal 111 is set so that the drive current signals 111 are equal.

As described above, even when the control is switched from the APC control to the ACC control, the bias level drive current signal 10 is almost the same as the output value of the APC circuit immediately before the switch.
8 will be output.

As described above, the optical information recording / reproducing apparatus according to the first embodiment causes the semiconductor laser light source (LD2) to emit pulse light based on a predetermined light emission rule, and emits the semiconductor laser light onto a recording medium (optical disk). Irradiation is performed, and a recording medium is channeled based on a predetermined recording modulation method by using ternary laser power of a bias level (bias power: Pb), an erase level (erase power: Pe), and a peak level (peak power: Pw). Information consisting of a pulse having a length equal to or greater than 1 (N) times the clock period (T) is recorded, information recorded on the recording medium is erased, the recording medium is initialized, and information recorded on the recording medium is initialized. To play.

The bias level current driver 7
Perform the following functions (1) to (12). (1) The laser drive current value of the semiconductor laser light source (LD2) is controlled so that the emission power of the semiconductor laser light becomes constant according to the level change of the signal (power monitor current signal 109) corresponding to the laser power level. First laser power control means (APC control circuit)

(2) Second laser power control means (ACC control circuit) for controlling the laser drive current value of the semiconductor laser light source (LD2) at a constant value irrespective of the laser power level, and the first laser power Switching means (laser drive circuit switching device) for switching between the control means (APC control circuit) and the second laser power control means (ACC control circuit)

(3) At the time of recording on a recording medium, the laser power at the erase level (erase power: Pe) is detected, and the laser power is controlled based on the laser power at the erase level (erase power: Pe). At the same time, a sampling pulse (sampling signal 113) output according to the data length of the information to be recorded on the recording medium for detecting the laser power of the erase level (erase power: Pe) is output at intervals within a predetermined period. In this case, the switching means switches to the first laser power control means (APC control circuit), and controls the laser drive current value by a control signal from the first laser power control means (APC control circuit). If the pulse (sampling signal 113) is not output for the predetermined period or more, The second laser power control means (AC
C control circuit) and means for controlling the laser drive current value by the control signal from the second laser power control means (ACC control circuit).

(4) The first laser power control means (A
PC control circuit) to the second laser power control means (A
CC control circuit) to output the sampling pulse (sampling signal 113), and then switch to the first laser power control means (APC control circuit) again by the switching means, and switch to the first laser power control means (APC control circuit). Means for controlling the laser drive current value by a control signal from the control circuit)

(5) The first laser power control means (A
The semiconductor laser light source (LD2) emits light at the bias level (bias power: Pb) by a laser drive current control signal output from the PC control circuit) or the second laser power control means (ACC control circuit). Driving a current, the semiconductor laser light source (LD2)
Efficiency characteristics of the laser light emitted from the laser (differential efficiency: η)
Means for driving a current for causing the semiconductor laser light source (LD2) to emit light at the erase level (erase power: Pe) or the peak level (peak power: Pw) by superimposing a current according to the above on the laser light.

(6) The sampling pulse (sampling signal 113) is used as a trigger input, and the switching means (laser drive circuit switching device) receives the second laser power control means (ACC) a predetermined period after the trigger input.
Switching signal output means (monostable multivibrator 714) for outputting a second laser power control switching signal to be switched by the control circuit)

(7) When the sampling pulse (sampling signal 113) is not output for the predetermined period or longer, the switching signal output means (monostable multivibrator 714) switches the switching means (laser drive circuit switching device).
When the second laser power control switching signal (ACC control switching signal 750) falls and then the sampling pulse (sampling signal 113) is output, the second laser power control switching signal (ACC control switching signal 750) is output. Means to control to stand up

(8) The first laser power control means (A
Control signal (APC control circuit output signal) output from the PC control circuit) and the second laser power control means (ACC).
A differential signal output means (A) for outputting a differential signal with a control signal (ACC control circuit output signal) output from the control circuit)
PC circuit output feedback circuit 706)

(9) The second laser power control means (A
During the period when the laser drive current value is controlled by the PC control circuit), the signal (power monitor signal) corresponding to the laser power level (power monitor signal) output to the second laser power control means (APC control circuit) is used. By feeding back the output signal of the differential signal output means (APC circuit output feedback circuit 706) to the first laser power control means (APC control circuit), the first laser power control means (AP
C means for holding the control signal output from the C control circuit at the same level as the control signal output from the second laser power control means (ACC control circuit)

(10) The control signal (APC control circuit output signal) output from the first laser power control means (APC control circuit) and the second laser power control means (A
Comparison signal output means (APC / ACC output signal comparison circuit) for outputting a comparison signal as a result of comparing a control signal (ACC control circuit output signal) output from the CC control circuit)

(11) The control signal (the APC control circuit output signal and the ACC control circuit output signal) is periodically compared by the comparison signal output means so that the control signal (the APC control circuit output signal and the ACC control signal) are compared. Means for controlling the control signal (ACC control circuit output signal) output from the second laser power control means (ACC control circuit) so that the circuit output signal always has substantially the same level.

(12) Means for setting the timing of outputting the sampling pulse (sampling signal 113) when a period in which information to be recorded on the recording medium is “0” occurs for a predetermined period or more.

In the optical information recording / reproducing apparatus of the first embodiment, the case where the period for switching from the APC control to the ACC control is 150 ms has been described. Should be set.

In the optical information recording / reproducing apparatus of the first embodiment, when recording, erasing, initializing, and reproducing information are performed by using three values of laser power of a bias level, an erase level, and a peak level, respectively, when recording, As the laser power control, the erase level laser power is detected, the laser power is controlled based on the detected erase level laser power, and according to the data length of the recording information to detect the erase level laser power. If the sampling pulse output at a predetermined interval is output within the predetermined period, the laser drive current value is controlled by the APC control circuit, and if the sampling pulse is not output for the predetermined period or more, the laser is switched to the ACC control circuit. Since the laser drive current value is controlled, the sampling signal of the sample and hold circuit Even if no output more than a predetermined period, it is possible to control the laser power accurately.

When the sampling pulse is output after the laser power control circuit is switched from the APC control circuit to the ACC control circuit, the laser drive current value is controlled again by switching to the APC control circuit. Can be made as short as possible, and the laser power can be controlled more accurately.

Further, a current for emitting light at a bias level is driven based on a control signal of a laser drive current output from the APC control circuit or the ACC control circuit, and a current corresponding to the differential efficiency characteristic of the laser light is generated. Drive the current for emitting light at the erase level or the peak level by superimposing on the bias level,
It is possible to accurately control the laser power of each of the erase level and the peak level.

When the monostable multivibrator uses a sampling pulse as a trigger input, outputs a ACC control circuit switching signal to the laser drive circuit switching circuit after a predetermined period of the trigger input, and the sampling pulse is not output for a predetermined period or more. The ACC control circuit switching signal output from the monostable multivibrator to the laser drive circuit switching circuit falls, and then the ACC control circuit switching signal rises when a sampling pulse is output. Even if the sampling signal is not output for a predetermined period or more, the laser power can be accurately controlled.

Further, a differential signal of an APC control circuit output signal output from the APC control circuit and an ACC control circuit output signal output from the ACC control circuit is output by the APC control circuit output feedback circuit, and the laser is output by the ACC control circuit. During the power control period, the output signal from the APC control circuit output feedback circuit is fed back to the APC control circuit instead of the power monitor signal output to the APC control circuit, whereby the output signal of the APC control circuit is changed to the ACC control circuit. Since the output signal is kept at the same level,
The output of the APC control circuit can be prevented from being saturated during the C control period, and the output signal of the APC control circuit can be quickly settled when returning from the ACC control to the APC control.

The APC / ACC output signal comparison circuit outputs a comparison signal obtained by comparing the APC control circuit output signal output from the APC control circuit with the ACC control circuit output signal output from the ACC control circuit. The circuit output signal and the ACC control circuit output signal are periodically compared so that the APC control circuit output signal and the ACC control circuit output signal always have substantially the same level.
Since the C control circuit output signal is controlled, the APC
Even when the control is switched to the CC control, the laser power can be accurately controlled.

Further, since the sampling pulse is output at the timing when the period in which the record information is "0" occurs for a predetermined period or more, the APC control circuit can be constituted by a low-band power detection / control circuit.

(Second Embodiment) Next, an optical information recording / reproducing apparatus according to a second embodiment of the present invention will be described. FIG.
FIG. 9 is a timing chart of main signals output by the CPU of the optical information recording / reproducing apparatus of the second embodiment.

The optical information recording / reproducing apparatus according to the second embodiment has the function described in claim 1 of the present invention.
Its configuration is the same as that of the optical information recording / reproducing apparatus of the first embodiment described above. However, unlike the above, recording is performed on an optical disk which is a dye medium.

Therefore, the recording level is changed to the bias level (bias power: Pb) and the peak level (peak power: Pb).
Pw), and the level for sampling and holding is set to the bias level. Therefore, the erase power enable signal 101 output by the CPU 1 of the optical information recording / reproducing apparatus of the second embodiment is always at the low level "L" as shown in FIG.

Further, the media type selection signal 116 shown in FIG. 2 becomes low level “L” and the power monitor signal 1
10 is amplified by an amplifier 701, and the sample-and-hold circuit 7
At 02, the signal is sampled and held and output to the APC circuit 705.

That is, the optical information recording / reproducing apparatus of the second embodiment irradiates a semiconductor laser light source (LD2) with a semiconductor laser beam on a recording medium (optical disk) by causing the semiconductor laser light source (LD2) to emit pulse light based on a predetermined light emission rule. For the recording medium, an integer (N or more) of one or more of a channel clock cycle (T) based on a predetermined recording modulation method by a binary laser power of a bias level (bias power: Pb) and a peak level (peak power: Pw). 2.) Recording information consisting of double-length pulses and reproducing the information recorded on the recording medium.

The bias level current driver 7
Perform the functions of (20) to (23) shown below. (20) A laser driving current value of the semiconductor laser light source is controlled such that the emission power of the semiconductor laser light becomes constant according to the level change of the signal (power monitor current signal 109) corresponding to the laser power level. 1 laser power control means (APC control circuit)

(21) Second laser power control means (ACC control circuit) for controlling the laser drive current value of the semiconductor laser light source at a constant value irrespective of the laser power level (22) The first laser power control Switching means (laser drive circuit switching device) for switching between means (APC control circuit) and the second laser power control means (ACC control circuit)

(23) At the time of recording on the recording medium, the laser power of the above-mentioned bias level (bias power: Pb)
Is detected, the laser power is controlled based on the laser power at the bias level (bias power: Pb), and recording is performed on the recording medium to detect the laser power at the bias level (bias power: Pb). When the sampling pulse (sampling signal 113) output according to the data length of the information is output at intervals within a predetermined period, the switching means switches to the first laser power control means (APC control circuit), and The laser drive current value is controlled by a control signal from the first laser power control means (APC control circuit). If the sampling pulse (sampling signal 113) is not output for the predetermined period or more, the second laser power control means (ACC) Control circuit) and switches the second laser power control means (A Means for controlling the laser driving current value by the control signal from the C controller)

In the optical information recording / reproducing apparatus of the first embodiment, when recording and reproducing information with binary laser power of a bias level and a peak level, respectively, when controlling the laser power during recording, the bias level and the peak level are controlled. The laser power is detected, the laser power is controlled based on the detected laser power of the bias level, and a sampling pulse output according to the data length of the recording information for detecting the laser power of the bias level is determined. When output at intervals within the period, APC
The laser drive current value is controlled by the control circuit, and when the sampling pulse is not output for a predetermined period or more, the laser drive current value is controlled by switching to the ACC control circuit.
Even when the sampling signal of the sample and hold circuit is not output for a predetermined period or more, the laser power can be controlled accurately.

(Third Embodiment) Next, an optical information recording / reproducing apparatus according to a third embodiment of the present invention will be described. FIG.
FIG. 11 is a timing chart of various signals related to ACC control by a bias level current driver of the optical information recording / reproducing apparatus of the third embodiment. FIG. 8 is a block diagram showing a configuration of a counter provided in the optical information recording / reproducing apparatus of the third embodiment.

The optical information recording / reproducing apparatus according to the third embodiment has the function described in claim 6 of the present invention.
Its configuration is substantially the same as that of the optical information recording / reproducing apparatus of the first embodiment described above, but is different from the monostable multivibrator 714 of the circuit for generating the timing of switching from the APC control to the ACC control as shown in FIG. The counter 7112 having a simple configuration is used.

As shown in FIG. 8, this counter 7112
Is relatively low frequency (eg, 1M
Hz), the counter 7112 outputs a low-level “L” signal when the counter 7112 has counted a predetermined count value or more, and resets with the sampling signal 113 to output a high-level “H” signal.

The counter 7112 is counted by the clock 7111, and outputs an ACC control switching signal 750 to the switches 710, 711 and 712 when a predetermined count (for example, 150 counts, 150 μs) or more is counted. This counter 7112 outputs the sampling signal 1
Since the configuration is such that the signal is reset at the rise of the signal 13, the high-level "H" signal is continuously output while the sampling signal 113 is output within the interval of 150 .mu.s.

As shown in FIG. 7, if the sampling signal 113 is not output for more than 150 μs,
112 sets the ACC control switching signal 750 to low level “L”.
To Therefore, similarly to the optical information recording / reproducing apparatus of the first embodiment, the control of the semiconductor laser light is switched to the ACC control. When the sampling signal 113 is output at that time, the counter 7112 is reset, and the ACC control switching signal 750 is set to the high level “H”, and the AP 7112 is quickly reset.
Return to C control.

In the optical information recording / reproducing apparatus of the third embodiment, an independent clock is used as a counter clock, but a clock obtained by appropriately dividing a channel clock may be used.

The optical information recording / reproducing apparatus according to the third embodiment operates at a predetermined clock frequency and resets a count value by a sampling pulse. Output control circuit switching signal,
If the sampling pulse is not output for a predetermined period or more, the ACC control circuit switching signal output from the counter to the laser drive circuit switching circuit is caused to fall, and then, when the sampling pulse is output, the counter is reset to switch the ACC control circuit. Since the signal rises, the laser power can be accurately controlled even when the sampling signal of the sample hold circuit is not output for a predetermined period or more.

[0120]

As described above, according to the optical information recording / reproducing apparatus of the present invention, the laser power of the semiconductor laser light source can be accurately controlled even when the sampling signal of the sample hold is not output for a predetermined period or more. Can be.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention;
1 is a block diagram illustrating a functional configuration of a main part of an optical information recording / reproducing device according to one embodiment.

FIG. 2 is a block diagram showing an internal configuration of the bias level current driving device shown in FIG.

FIG. 3 is a timing chart of main signals output by a CPU shown in FIG. 1;

FIG. 4 is a diagram showing a relationship between a driving current output from the bias level current driving device shown in FIG. 2 and light emission power of a laser diode.

5 is a timing chart of various signals related to ACC control by the bias level current driver shown in FIG. 2;

FIG. 6 shows a CP of the optical information recording / reproducing apparatus according to the second embodiment;
It is a timing chart figure of the main signal which U outputs.

FIG. 7 is a timing chart of various signals related to ACC control by a bias level current driver of the optical information recording / reproducing apparatus of the third embodiment.

FIG. 8 is a block diagram showing a configuration of a counter provided in the optical information recording / reproducing apparatus of the third embodiment.

FIG. 9 is a waveform diagram showing a multi-pulse waveform using a conventional recording power.

FIG. 10 is a waveform diagram showing a conventional multi-pulse waveform.

FIG. 11 is a waveform chart showing an example of a conventional recording waveform.

[Explanation of symbols]

 1: CPU 2: laser diode (LD) 3: monitor photodiode (monitor PD) 4: LD driver 5: I / V conversion circuit 7: bias level current driver 8: erase level current driver 9: peak level current Driving devices 10, 11: D / A converter 101: erase power enable signal 102: peak power enable signal 104: erase level control signal 105: peak level control signal 106: erase level superimposed current signal 107: peak level superimposed current signal 108: Bias level drive current signal 109: Power monitor current signal 110: Power monitor signal 111: ACC drive current signal 112: Target power value signal 113: Sampling signal 114: APC / ACC output comparison signal 115: Bias level drive current digital Signal 116: media type selection signal 701, 703: amplifier 702, 704: sample hold circuit 705: APC circuit 706: APC circuit output feedback circuit 707: comparator 708: inverting amplifier 709, 710, 711, 712: switch 713: A / D converter 714: monostable multivibrator 750: ACC control switching signal

Claims (9)

[Claims] 1. A semiconductor laser light source irradiates a laser beam onto a recording medium by causing a semiconductor laser light source to emit pulse light based on a predetermined light emission rule, and a predetermined laser power of a bias level and a peak level is applied to the recording medium. An optical information recording / reproducing apparatus for recording information composed of pulses having a length of an integer multiple of 1 or more of a channel clock cycle based on the recording modulation method and reproducing the information recorded on the recording medium, wherein the laser power level Controlling the laser drive current value of the semiconductor laser light source so that the emission power of the laser light becomes constant in accordance with the level change of the signal corresponding to
Laser power control means; second laser power control means for controlling a laser drive current value of the semiconductor laser light source at a constant value irrespective of the laser power level; first laser power control means and the second laser Switching means for switching power control means; detecting the laser power of the bias level during recording on the recording medium, controlling the laser power based on the laser power of the bias level, and controlling the laser power of the bias level. If the sampling pulse output according to the data length of the information to be recorded on the recording medium for detecting the is output at intervals within a predetermined period, by switching to the first laser power control means by the switching means, The laser drive current value is controlled by a control signal from the first laser power control means, When the sampling pulse is not output for the predetermined period or more, a means for switching to the second laser power control means and controlling a laser drive current value by a control signal from the second laser power control means is provided. Optical information recording / reproducing device. 2. A ternary laser having a bias level, an erase level, and a peak level on a recording medium by irradiating a laser beam onto a recording medium by causing a semiconductor laser light source to emit pulse light based on a predetermined emission rule. Recording information consisting of a pulse having a length of an integral multiple of 1 or more of a channel clock cycle based on a predetermined recording modulation method by power, erasing information recorded on the recording medium, initializing the recording medium, and An optical information recording / reproducing apparatus for reproducing information recorded on a recording medium, comprising: First to control the drive current value
Laser power control means; second laser power control means for controlling a laser drive current value of the semiconductor laser light source at a constant value irrespective of the laser power level; first laser power control means and the second laser Switching means for switching power control means; detecting the erase-level laser power during recording on the recording medium; controlling the laser power based on the erase-level laser power; If the sampling pulse output according to the data length of the information to be recorded on the recording medium for detecting the is output at intervals within a predetermined period, by switching to the first laser power control means by the switching means, The laser drive current value is controlled by a control signal from the first laser power control means, When the sampling pulse is not output for the predetermined period or more, a means for switching to the second laser power control means and controlling a laser drive current value by a control signal from the second laser power control means is provided. Optical information recording / reproducing device. 3. The optical information recording / reproducing apparatus according to claim 1, wherein the first laser power control means switches to the second laser power control means to output the sampling pulse, and the switching means outputs the sampling pulse. An optical information recording / reproducing apparatus, further comprising means for switching to the first laser power control means again to control a laser drive current value by a control signal from the first laser power control means. 4. The optical information recording / reproducing apparatus according to claim 2, wherein the semiconductor laser light source is biased by a laser drive current control signal output from the first laser power control means or the second laser power control means. The semiconductor laser light source emits light at the erase level or the peak level by driving a current for emitting light at the level and superimposing a current corresponding to the differential efficiency characteristic of the laser light emitted from the semiconductor laser light source on the laser light. An optical information recording / reproducing apparatus, comprising: means for driving a current for causing a current to flow. 5. The optical information recording / reproducing apparatus according to claim 1, wherein the sampling pulse is used as a trigger input, and the switching means is provided to the second laser power control means a predetermined period after the trigger input. A switching signal output unit that outputs a second laser power control switching signal to be switched; and a second laser power control switching signal that is output from the switching signal output unit to the switching unit when the sampling pulse is not output for the predetermined period or longer. An optical information recording / reproducing apparatus, comprising: means for controlling the second laser power control switching signal to rise when the sampling pulse is output after the falling. 6. The optical information recording / reproducing apparatus according to claim 1, wherein the optical information recording / reproducing apparatus operates based on a predetermined clock frequency, resets a count value by the sampling pulse, and performs a predetermined count after the count value is reset. A counting means for outputting a second laser power control switching signal for causing the switching means to switch to the second laser power control means; and a second means for outputting from the counting means to the switching means when the sampling pulse is not output for the predetermined period or more. (2) Optical information characterized by comprising means for resetting the counting means when the sampling pulse is output after the falling of the laser power control switching signal and for controlling the second laser power control switching signal to rise. Recording and playback device. 7. The optical information recording / reproducing apparatus according to claim 1, wherein a control signal outputted from said first laser power control means and a control signal outputted from said second laser power control means are outputted. A differential signal output unit for outputting a differential signal with respect to a control signal; and a laser power output to the second laser power control unit during a period in which a laser drive current value is controlled by the second laser power control unit. The output signal of the differential signal output means is fed back to the first laser power control means instead of the signal corresponding to the level of the first laser power control means.
An optical information recording / reproducing apparatus comprising: means for holding a control signal output from a laser power control means at the same level as a control signal output from the second laser power control means. 8. The optical information recording / reproducing apparatus according to claim 1, wherein a control signal outputted from said first laser power control means and a control signal outputted from said second laser power control means are outputted. A comparison signal output means for outputting a comparison signal as a result of comparing the control signals; and the second control signal being periodically compared by the means so that the two control signals always have substantially the same level. An optical information recording / reproducing apparatus comprising means for controlling a control signal output from a laser power control means. 9. The optical information recording / reproducing apparatus according to claim 1, wherein the timing at which the sampling pulse is output is such that a period in which information recorded on the recording medium is 0 is equal to or longer than a predetermined period. An optical information recording / reproducing apparatus, characterized in that a means for performing an occurrence is provided.